From 2a14759a03a0a57b2fc99b1e416180788b8ba24c Mon Sep 17 00:00:00 2001 From: Oliver Neukum Date: Mon, 4 Apr 2016 14:30:53 +0200 Subject: [PATCH] cdc-acm: fix crash if flushed with nothing buffered Under some circumstances acm_tty_flush_chars() is called with no buffer to flush. We simply need to do nothing. Signed-off-by: Oliver Neukum Reported-by: Torsten Hilbrich Signed-off-by: Greg Kroah-Hartman --- drivers/usb/class/cdc-acm.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c index 83fd30b0577c..a6c4a1b895bd 100644 --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -744,11 +744,15 @@ static void acm_tty_flush_chars(struct tty_struct *tty) int err; unsigned long flags; + if (!cur) /* nothing to do */ + return; + acm->putbuffer = NULL; err = usb_autopm_get_interface_async(acm->control); spin_lock_irqsave(&acm->write_lock, flags); if (err < 0) { cur->use = 0; + acm->putbuffer = cur; goto out; } -- 2.34.1